Eq.(1.2) is called a correction functional. The variational iteration method proposed by Ji-Huan He has been shown to solve effectively, easily, and accurately a large class of non-linear problems with approximations converging rapidly to accurate solutions. For linear problems, its exact solution can be obtained by only one iteration step due to the fact that the Lagrange multiplier can be exactly identified.
The variational iteration method is proposed to solve the generalized diode equation, by suitable choice of the initial trial-function, one step iteration leads to an high accurate solution, which is valid for the whole solution domain [7]. D and C [16] applied the variational iteration method to non-linear anelastic model describing the acceleration of the relaxation process in the presence of the vibrations. The combination of a perturbation method, variational iteration method, method of variation of constants and averaging method to establish an approximate solution of one degree of freedom weakly non-linear systems was proposed in [17]. The application of the variational iteration method to non-linear fractional differential equations can be found in details in [4]. Moreover, the method was successfully applied to delay differential equations in [2], to autonomous ordinary differential systems [6], and other fields [3,5].
In this paper, we implement the variational iteration method for finding the exact solution of the Helmholtz equation. The Helmholtz equation will be handled more easily, quickly, and elegantly by implementing the variational iteration method rather than the traditional methods for the exact solutions as well as approximate solutions, without suffering traditional difficulty, namely we consider: